As shown in a cross sectional view of FIG. 8 taken along a tube drawing direction, a tubular fuel cell is conventionally configured to include an internal electrode 10, a first catalytic layer 12, an electrolytic layer 14, a second catalytic layer 16, an exterior coil 18, and a resin seal 20. FIG. 9 is a cross sectional view taken along a line A-A in FIG. 8. As shown in FIG. 9, the internal electrode 10, the first catalytic layer 12, the electrolytic layer 14, and the second catalytic layer 16 are sequentially laminated in that order from inside in the form of a substantially coaxial cylinder.
When a plurality of such tubular fuel cells are assembled and combined into a module, it is preferable that the cells be placed at predetermined intervals that will enable them to supply fuel gas or oxidant gas to the cells as uniformly as possible to ensure that heat resulting from the chemical reactions will be preferably removed. Japanese Patent Laid-Open Publication No. 2002-298877 discloses a spacer structure in a tubular fuel cell in which a gas sealing part is prevented from receiving a load, thereby enabling reduction in occurrence of a cell tube failure.
Conventional art, however, has required, in addition to spacers used for maintaining spacings between a plurality of tubular fuel cells at a predetermined distance, the current collecting wires be independently connected to establish parallel connection between internal electrodes and between exterior coils in the plurality of tubular fuel cells combined into the module. Such a system of connecting the current collecting wires is complicated, hampering production of inexpensive fuel cell modules. Further, there has been a necessity to provide electrodes for current collection in addition to the spacers, which obstructs efforts to miniaturize the fuel cell module.
In particular, when several to tens of thousands of ultra-thin tubular fuel cells measuring approximately several millimeters in diameter are assembled and combined into a module while securing a several millimeter cell spacing, electrical connection between the cells combined into the module should be established, which necessitates a highly accurate wiring technique and a great amount of time and effort. Accordingly, the resulting operation or process of manufacturing a fuel cell module is complicated and difficult, thereby increasing manufacturing costs.